At a customer’s facility they used a long hydraulic cylinder in a track in the floor to move a small rail car into an oven. The maintenance manager was tired of installing rebuilt cylinders only to find they leaked, so he decided to test one before he installed it. He hooked it to a large flow power unit in the maintenance shop. The long stroke, large diameter rod began to accelerate to near warp speed. When it reached the end of the stroke, the end cap didn’t have a chance of holding.
The rod (now a spear) shot out of the cylinder, traveled through the sheet metal wall and speared a Chevrolet Vega in the parking lot. The Vega was owned by a machinist in the shop, and he was the first to admit it was a fitting end for the car.
Hydraulic cylinders can exert tons of force because of hydraulic pressure confined to a small area. Mounting brackets at both ends of the stroke must be firmly mounted and designed to withstand the force. Use test stands with calibrated hydraulic pressure and flow whenever testing a cylinder.
Safety is your number one concern. Prepare an emergency shut-off procedure before testing and always double-check your loads. Stay clear of any moving cylinder that may have the potential to break free of its mounts. Better yet, don’t take chances at all; call an expert to rebuild and test your hydraulic cylinders before installing them. Respect the pressure.
Lessons Learned are contributed by Cleveland-based Applied Industrial Technologies’ Fluid Power Specialists. Tom Nash is Applied’s Product Manager - Fluid Power Products. Contact him at (216) 426-4257, firstname.lastname@example.org, or visit www.applied.com.